Bayern Munich head coach Julian Nagelsmann admits Tuesday's Champions League opponent Barcelona will miss Lionel Messi's "extravagance" but believes they are not much weaker without him.

Messi left Barcelona in the off-season to join Paris Saint-Germain after a glittering career at Camp Nou.

The Catalans have started life domestically without Messi with seven points from three games in LaLiga, while they will commence their Champions League campaign on Tuesday against Nagelsmann's Bayern in Barcelona.

"Barcelona definitely don't have the extravagance of a Messi any more. But they also have other players who can play a very important role if you take Frenkie de Jong and Pedri for example," Nagelsmann said at the pre-game news conference.

"We are ready for anything. I don't believe they are much weaker. The future will show if they are any better. But we definitely want to take three points."

Barcelona have a variety of selection issues with injuries to Ousmane Dembele, Ansu Fati, Martin Braithwaite and Sergio Aguero, while Nagelsmann was coy on Serge Gnabry's availability.

Gnabry was substituted with a back problem in Saturday's 4-1 Bundesliga win over RB Leipzig, along with Robert Lewandowski for "precautionary" reasons with a groin complaint.

"We'll have to make a late decision on that one," Nagelsmann said about Gnabry.

"Gnabry will travel. [Corentin] Tolisso will not. [Kingsley] Coman is in the squad but not an option to start. It's looking good for Lewandowski again though."

Bayern thrashed Barcelona 8-2 in the 2020 Champions League quarter-final played as a one-off in Lisbon, adding further spice to their opening Group E fixture.

"Being the favorites or not the favorites is always more of a subject for the media," he said. "Two world-class clubs face each other."